1. Field of the Invention
This invention relates to a method of producing an atomized liquid that is to be conveyed in a carrier gas.
2. Background Information
The atomization or vaporization of a liquid into a carrier gas is particularly difficult if relatively small mass streams of less than two kilograms per hour are to be atomized at a high degree of fineness (droplet diameter less than 100 .mu.m); that is, ultrasmall liquid droplets must be produced. The atomization with the aid of nozzles and the liquid to be atomized under high pressure encounters natural limits with respect to the realizable smallness of the droplets since the required liquid flow rate must be produced with extremely small nozzle flow cross sections. For example, in a series of applications, the geometrical transverse dimensions for mass streams in a range of two kilograms per hour lie between 0.1 and 0.3 mm which in practice leads to clogging and non-reproducible atomization rates. Moreover, it cannot be avoided here that insufficient break-off of the liquid stream causes larger droplets to be formed repeatedly at the nozzle itself; in the subsequent utilization of the resulting mist such larger droplets have a disadvantageous effect. For example, in the atomization of heating oil where, in particular, the larger droplets contained in the collections of droplets cause the known problems of ancillary mist field formation in the region of the root of the flame and thus insufficient combustion with relatively long flames. Another drawback of the prior art atomization methods with the aid of nozzles is that, even if high strength materials are employed, cavitation phenomena occur in the region of the nozzle opening which, after a corresponding period of operation, lead to worsening of the atomization result. This occurs the earlier, the greater the degree of atomization and, connected therewith, the greater the admission pressure to be exerted onto the liquid.
In order to overcome these drawbacks, atomizer-vaporizer devices are known which are operated with a driving gas, particularly air, to atomize a liquid. Such devices are, for example, oil vaporizers for the lubrication of bearings or pneumatic oil atomizers for heating oil burners used in private homes or steam pressure atomizers used in industry. In these devices, the liquid to be atomized, for example the heating oil, is atomized by means of compressed air or steam in an injector nozzle or at curved guide faces. Although this yields good atomization rates with small throughputs, there exists the drawback in the amount of equipment required to generate the compressed air, for example for the pneumatic atomizers. The required air pressures of 0.6 to 1.2 bar and volume streams of 600 to 1200 dm.sup.3 /h necessitates the use of compressors since it is technically impossible to realize such increases in pressure with blowers.